Article: Anatomy, patterns of occurrence, and nature of the conulariid schott

Conulariid specimens that terminate adapically in a transverse wall, or schott, have been interpreted in several ways. These interpretations have been based more on analogy with extant organisms than on evaluation of fossil material. Currently favoured interpretations are that (1) schott-bearing specimens represent individuals that were severed, in life, by currents; (2) schott-bearing specimens were free-swimming individuals; (3) schott-bearing specimens represent non-injured, sessile individuals that retracted the apical part of their soft body toward the oral end, as part of their normal life history. Examination of the test cavity of conulariid specimens that do not terminate in a schott, and analysis of the frequency of occurrence of schott-bearing specimens in low- versus high-energy sedimentary deposits, indicate that the most likely interpretation of schott-bearing specimens is that they represent living individuals severed by currents. Proponents of a scyphozoan affinity for conulariids have generally interpreted schott-bearing specimens as conulariid medusae, one of the alternatives not favoured by the present analysis. In spite of this, the interpretation of schott-bearing specimens as severed individuals is consistent with the hypothesis that conulariids and scyphozoans were closely related.